In recent years, hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), battery electric vehicles (BEV) have been developed and commercialized from the viewpoint of environmental protection and energy saving. As the energy source of such electric vehicle, a large-scale secondary battery which is repeatedly chargeable and dischargeable is an essential technology. In particular, an organic electrolyte storage battery is a potent battery because it is higher in operating voltage and more likely to produce high power than the other secondary batteries containing a nickel-hydrogen cell and thus becomes increasingly important as the electric power source of an electric vehicle. Various developments therefore have been made. For example, it has been proposed to use various additives in order to guarantee a safety against burning or the like of a lithium-ion battery in overcharged state (for example, see Patent Literatures 1 to 3 below).
On the other hand, an improvement in initial storage capacity that affects the possible cruising range has been sought. That is, the BEV, among the electric vehicles, is driven only by an electric motor with a secondary battery as the power source and thus the cruising range is determined by the capacity of the battery. An electric vehicle equipped with a larger capacity of battery can, therefore, travel a longer distance but the electric energy (initial storage capacity) that can be installed on a single vehicle is limited.